WORCESTER — Ziti and sausage awaited Thomas A. Feraco Tuesday night, a late bite that would go uneaten after his phone rang.

Instead of eyeing a pasta dinner, the accident reconstruction police officer surveyed a glass-strewn Shrewsbury Street as he mapped the scene of a serious motorcycle accident.

Brake fluid and gasoline were spattered on the street as members of the Worcester Police Department's Accident Reconstruction Unit went about their business, untangling a mangled mess of metal, glass, motor oil, and blood. It was the second serious motorcycle accident in two days.

"Every single time you go to a crash and you see a lot of trauma, it bothers you. For us, we try to separate that and do our job," said Lt. Timothy P. Walsh, the unit supervisor. "A lot of guys don't want to show emotion, but if you are a human being, and you see that type of trauma consistently, it is going to affect you some way.

The Police Department recently made some changes that enable the 10-member unit to spend more time investigating serious traffic accidents, which can be time-consuming, and requires special skills. Traffic enforcement across the city was shifted to the police department's patrol division.

Time is of the essence when it comes to reconstructing accidents.

Road and lighting conditions at the time of the accident are vital pieces of information. The friction of the surface where the accident occurred is tested. Paint swipes in vehicle accidents are reviewed. Skid mark lengths are measured. A special system called Total Station maps out the accident. Search warrants are issued for cellphone records and for the results of blood tests.

Sometimes the unit will recreate the accidents and run the scenario over and over. Officers take the victim's age and use that to judge how fast a pedestrian might have walked. They will use the same make and model of the vehicle in the fatal pedestrian accident.

"We're seeing an influx of pedestrian fatals and accidents. You drive anywhere in Worcester, people just walk into the road," Officer Feraco said. "Pedestrians do have some sort of responsibility."

There are accidents that linger, such as the one in March on Franklin Street, in which a 3-year-old was killed and his two brothers injured. The driver was the child's mother. She has been charged with motor vehicle homicide and reckless endangerment.

"Finding out a 3-year-old passed away made everyone on the team distraught," Officer Feraco said. "It (the accident) could have been avoided."

Members of the team wonder what is waiting when Sgt. John J. Fallavollita calls them.

Sgt. Fallavollita, the first accident reconstruction officer on the department who started in the Traffic Division in the 1980s, has seen it all.

He said fatal accidents have been declining, which could be the result of better-made cars, or better seat belts. Speed and alcohol are a significant factor in many major crashes, and as cell phones crept into society, driver distraction began increasing as a cause of accidents.

Technology has helped investigators do their job. They can find a vehicle's speed, braking, and more information from a vehicle's crash data recorder, which registers information about an accident. All the information gleaned in an investigation is punched into a computer system that helps determine what happened.

While computer chips and software programs are a big aid, Officer Feraco likes to start off an investigation in an old school way.

At a recent accident scene, he pulled out a piece of paper with a mathematical equation to determine a vehicle's speed at the time of an accident. It takes him 30 seconds to go over the equation.

"He says it's simple, but it comes easy to him," Lt Walsh said.

No one knows when the next call will come in.

"Any time of the day, early morning," Sgt. Fallavollita said. "It is just unpredictable when the crashes will occur."